Search results for "SPECTRA"

CHANGES OF ELECTRONIC NOISE INDUCED BY OSCILLATING FIELDS IN BULK GaAs SEMICONDUCTORS

2008

A Monte Carlo study of hot-electron intrinsic noise in a n-type GaAs bulk driven by one or two mixed cyclostationary electric fields is presented. The noise properties are investigated by computing the spectral density of velocity fluctuations. An analysis of the noise features as a function of the amplitudes and frequencies of two applied fields is presented. Numerical results show that it is possible to reduce the intrinsic noise. The best conditions to realize this effect are discussed.

New microsecond isomers in 189, 190Bi

2001

New microsecond isomers in the neutron-deficient isotopes 189g, 190Bi have been identified after in-flight separation by the velocity filter SHIP. The evaporation residues were identified on the basis of delayed recoil-γ/X-ray, recoil-γ/X-ray-α and excitation function measurements. The systematics of the [ π1i 13/2]13/2+ excited states in the odd-mass Bi nuclei is discussed.

Spin-coupling topology in the copper hexamer compounds A2Cu3O(SO4)3 (A=Na, K)

2020

The compounds ${A}_{2}\mathrm{C}{\mathrm{u}}_{3}\mathrm{O}{(\mathrm{S}{\mathrm{O}}_{4})}_{3}$ $(A=\mathrm{Na},\phantom{\rule{0.16em}{0ex}}\mathrm{K})$ are characterized by copper hexamers that are weakly coupled to realize antiferromagnetic order below ${T}_{N}\ensuremath{\approx}3\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. They constitute quantum spin systems with $S=1$ triplet ground states. We investigated the energy-level splittings of the copper hexamers by inelastic neutron scattering experiments covering the entire range of the magnetic excitation spectra. The observed transitions are governed by very unusual selection rules that we ascribe to the underlying spin-coupling topology. This…

HINODE /EIS SPECTROSCOPIC VALIDATION OF VERY HOT PLASMA IMAGED WITH THE SOLAR DYNAMICS OBSERVATORY IN NON-FLARING ACTIVE REGION CORES

2012

We use coronal imaging observations with SDO/AIA, and Hinode/EIS spectral data, to explore the potential of narrow band EUV imaging data for diagnosing the presence of hot (T >~5MK) coronal plasma in active regions. We analyze observations of two active regions (AR 11281, AR 11289) with simultaneous AIA imaging, and EIS spectral data, including the CaXVII line (at 192.8A) which is one of the few lines in the EIS spectral bands sensitive to hot coronal plasma even outside flares. After careful coalignment of the imaging and spectral data, we compare the morphology in a 3 color image combining the 171, 335, and 94A AIA spectral bands, with the image obtained for CaXVII emission from the an…

Fundamental properties and atmospheric structure of the red supergiant VY CMa based on VLTI/AMBER spectro-interferometry

2012

We investigate the atmospheric structure and fundamental properties of the red supergiant VY CMa. We obtained near-infrared spectro-interferometric observations of VY CMa with spectral resolutions of 35 and 1500 using the AMBER instrument at the VLTI. The visibility data indicate the presence of molecular layers of water vapor and CO in the extended atmosphere with an asymmetric morphology. The uniform disk diameter in the water band around 2.0 mu is increased by \sim20% compared to the near-continuum bandpass at 2.20-2.25 mu and in the CO band at 2.3-2.5 mu it is increased by up to \sim50%. The closure phases indicate relatively small deviations from point symmetry close to the photospheri…

Strong Chromatic Microlensing in HE0047-1756 and SDSS1155+6346

2014

We use spectra of the double lensed quasars HE0047-1756 and SDSS1155+6346 to study their unresolved structure through the impact of microlensing. There is no significant evidence of microlensing in the emission line profiles except for the Ly$\alpha$ line of SDSS1155+6346, which shows strong differences in the shapes for images A and B. However, the continuum of the B image spectrum in SDSS1155+6346 is strongly contaminated by the lens galaxy and these differences should be considered with caution. Using the flux ratios of the emission lines for image pairs as a baseline to remove macro-magnification and extinction, we have detected strong chromatic microlensing in the continuum measured by…

Quons, coherent states and intertwining operators

2009

We propose a differential representation for the operators satisfying the q-mutation relation $BB^\dagger-q B^\dagger B=\1$ which generalizes a recent result by Eremin and Meldianov, and we discuss in detail this choice in the limit $q\to1$. Further, we build up non-linear and Gazeau-Klauder coherent states associated to the free quonic hamiltonian $h_1=B^\dagger B$. Finally we construct almost isospectrals quonic hamiltonians adopting the results on intertwining operators recently proposed by the author.

Extended SUSY quantum mechanics, intertwining operators and coherent states

2009

Abstract We propose an extension of supersymmetric quantum mechanics which produces a family of isospectral Hamiltonians. Our procedure slightly extends the idea of intertwining operators. Several examples of the construction are given. Further, we show how to build up vector coherent states of the Gazeau–Klauder type associated to our Hamiltonians.

Pulse Generation and Shaping Using Fiber Nonlinearities

2017

Iodine on a magnetized iron film evidence for a magnetic coupling

1993

Abstract Spin-resolved photoelectron spectra of iodine chemisorbed on a magnetized iron (110) surface have been taken using unpolarized VUV light. The partial spin spectra reveal the I 5p x and 5p z signals being split by up to 0.35 eV. This exchange splitting occurs due to hybridization of adsorbate and substrate bands as a consequence of the chemical bond of the halogen atoms to the iron surface.